2004-11-10_REVISION - M1999002

• Permit No: M1999002
• IBM Index Class Name: Revision
• Doc Date: 11/10/2004
• Doc Name: NPL & EWI Standards for G.W. Program
• From: American Soda LLP
• To: DMG
• Type & Sequence: TR4
• Media Type: D
• Archive: No

Permit#: I~l~(494•DOa Confidental?

AMERICA
SODA, L.L
Class: ~tl - Type-Seq.:
From: To:
Doc. Name: NGLf Etu= 4ln..~n,aL< ~ ~Mr
Doc. Date (if no date stamp): r!-l D_Du
Celina Akin
_ _ _ _ _,iental Engineer
2717 County Road 215
Parachute, CO 81635
Tuesday, November 9, 2004
Telephone [phone]
Facsimile [phone]
RECEIVED
IdOV ~ ~ 2004
Ms. Erica Crosby and Mr. Allen Sorenson
Colorado Division of Minerals and Geology
1313 Sherman Street, room 215
Denver, CO 80203
Dear Erica and Allen:
Division ~f Minerals and Geology
ENV250.04
This letter is in response to your letter dated October 26, 2004 regarding the determination of Numeric
Protection Levels and Early Warning Indicators as presented in Technical Revision #4 (TR-04) to
Permit No. M-1999-002 proposing to modify the ground water monitoring program for both the interim
status and for commercial production operations. Enclosed are two unbound copies of the sections of
TR-04 which have been modified in accordance with the modified Permit Condition Values (NPL and
EWI) and the requirement and schedule for full suite ground water monitoring on an annual frequency.
The schedule for verification sampling remains as stated in the original submittal of TR-04 as
discussed previously by electronic mail. I did not reprint Appendix A or Appendix C since nothing in
those pages has changed and they represent a large volume of the total document.
In addition to these changes, your letter requested a discussion of the difficulties experienced in
sampling and analyzing these samples which would help to account for some of the variations
observed in the data.
Regarding sampling, the issues relate primarily to the depth of the wells and to the size of the well
casings used. The water from the deep aquifers is typically very high in total dissolved solids. One of
my first experiences of sampling the ground water at Yankee Gulch involved a bailer sample that came
back to the surface completely full of crystals and no water. Initially, we could draw a sample of water
from one of the deeper dissolution surface wells and then come back to the location in the next month
and find the precipitation of heavy crystals plugging all of the sampling lines and in some cases even
the well casing such that reentering the well with a bailer to collect a sample required a heavy metal
rod to be forced through the blockage before the bailer could be lowered into the well. The crystals
formed in the casing at the point where the temperature of the water created the most optimal
conditions for precipitation. Water existed above and below the crystals but it was difficult to get
sampling equipment to the screened interval of the well. The original 21-4D well casing was damaged
during an attempt to dislodge a solid plug of crystals resulting in the drilling of a second offset well 21-
4DX on the same pad. Only the 21-3D well continues to provide a free flowing sample. This is due to
the lower conductivity of this completion in the uppermost part of the dissolution surface.
In many of the wells you can actually listen to the activity of gas as it evolves from the water in the
casing. It sounds like someone blowing through a straw with the end submerged. The sample water,
when brought to surface, is typically saturated with very small bubbles as the sample degasses from
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